1. Field of the Invention
This invention relates to an intake valve array for use in a four cycle internal combustion engine to increase volumetric efficiency, and specifically to a multiple poppet intake valve array that uses three or more poppet valve bodies for opening and sealing a single intake duct. The sum of the circumferential distances of the valve bodies are specifically determined to achieve optimum lift requirements earlier in the intake valve event, thus extending the duration of optimum valve opening area relative to the duct cross sectional area. The purpose of the invention is to quantitatively increase the duration period of optimum available intake valve open area (circumference times lift) of a single intake duct to enhance optimum charge flow into the combustion chamber during the intake event resulting in greater volumetric efficiency when compared with the duration of maximum valve open area available with one or two conventional intake poppet valves.
2. Description of Related Art
The use of one or two poppet intake valves in a single engine cylinder in a four cycle internal combustion engine is well known in the prior art. Typically each intake duct is serviced by one intake poppet valve. The cross sectional area of the duct and the area of the valve body at maximum lift are generally matched to prevent impedance of the charge velocity when the valve is fully open. Since the correct maximum valve open area is the valve body circumference times maximum lift, conventional valve lift distances exceeding 0.300 inches are employed. Such lift distances encroach the mechanical limits of the cam lobe profile and its valve train components due to time constraints during the intake event. The result is that maximum valve opening is achieved at only one limited instantaneous position over the entire intake event's duration at the cam lobe. This means that during the intake event, the maximum charge available in the intake duct as determined by its cross sectional area is not provided to the cylinder throughout the major portion of the valve event. Increasing the intake valve circumference to reduce lift does not solve the problem because duct enlargement necessary to accommodate the enlarge valve prior to the valve seat area would greatly exceed the upstream duct area creating diffusion, affecting charge velocity consistency throughout the system.
Applicant's invention differs significantly from the conventional intake valve technology in that three or more poppet valves are used for a single duct to increase total valve circumference, reducing valve lift distance required to achieve an extended duration period of maximum available charge flow for a single duct, greatly increasing the volumetric efficiency of the engine.